[D] Gryphognathus morrisoni [sG] [T]
Describer
Ryan, Evans, Currie, Brown & Brinkman 2011
Time
Cretaceous Late Santonian
Classification
Ornithischia Genasauria Cerapoda Marginocephalia Ceratopia Neoceratopia [Leptoceratopsidae]
Diet
Herbivore
Fossilsite
Milk River Formation, Deadhorse Coulee Member, Alberta, Canada
Info
Abstract
Two new leptoceratopsid neoceratopsians are described based on partial dentaries collected from the Dinosaur Park (Campanian) and Milk River (Santonian) formations of Alberta.
The new Campanian taxon has a unique dentary tooth shape not shared by other leptoceratopsid taxa, which has implications for the evolution of the Leptoceratopsidae.
The Santonian specimen represents the oldest known leptoceratopsid (~83 Ma), and probably represents the smallest adult-sized ceratopsian known from North America.
Holotype
ROM 56635, a partial right dentary
Etymology
Grypho (Latin, gyphus) + gnathus (Latin, jaw), referring to the legendary gryphon that had the body of a lion and the head of an eagle; a reference to the small hooked “chin” of the specimen. | The species epithet honors Ian Morrison, in recognition of his expert preparation of the holotype jaw and his contributions to vertebrate paleontology while working for the Royal Ontario Museum.
Locality and Horizon
Black Coulee (formerly Deadhorse Coulee), approximately 10 km east of Writing-on-Stone Provincial Park, Alberta, from the Deadhorse Coulee Member of the Milk River Formation (late Santonian). Detailed locality information is on record with the Royal Ontario Museum.
Gryphognathus morrisoni from the Santonian Milk River Formation is approximately 8 Ma older than U. koppelhusae and appears to be closely related to it. Gryphognathus appears to share with Unescoceratops the presence of a predentary symphysial “chin”, but, owing to breakage, we have chosen to code this character as indeterminate.
Additionally, the shape of the teeth and the degree of curvature of the ventral margin cannot be determined. We acknowledge that the holotype specimen, ROM 56635, is incomplete; however, we advocate recognition of the new taxon based on the presence of two autapomorphies; Gryphognathus appears to differ from Unescoceratops and all other leptoceratopsids in having a relatively deeper jaw, and in the shape of the posterior border of its predentary symphysial contact where it merges with the ventral margin.
As reconstructed, the foreshortened dentary of ROM 56635 is deeper than that of U. koppelhusae, and appears to be as deep, or deeper, than any other leptoceratopsid
Ryan, Evans, Currie, Brown & Brinkman 2011
Time
Cretaceous Late Santonian
Classification
Ornithischia Genasauria Cerapoda Marginocephalia Ceratopia Neoceratopia [Leptoceratopsidae]
Diet
Herbivore
Fossilsite
Milk River Formation, Deadhorse Coulee Member, Alberta, Canada
Info
Abstract
Two new leptoceratopsid neoceratopsians are described based on partial dentaries collected from the Dinosaur Park (Campanian) and Milk River (Santonian) formations of Alberta.
The new Campanian taxon has a unique dentary tooth shape not shared by other leptoceratopsid taxa, which has implications for the evolution of the Leptoceratopsidae.
The Santonian specimen represents the oldest known leptoceratopsid (~83 Ma), and probably represents the smallest adult-sized ceratopsian known from North America.
Holotype
ROM 56635, a partial right dentary
Etymology
Grypho (Latin, gyphus) + gnathus (Latin, jaw), referring to the legendary gryphon that had the body of a lion and the head of an eagle; a reference to the small hooked “chin” of the specimen. | The species epithet honors Ian Morrison, in recognition of his expert preparation of the holotype jaw and his contributions to vertebrate paleontology while working for the Royal Ontario Museum.
Locality and Horizon
Black Coulee (formerly Deadhorse Coulee), approximately 10 km east of Writing-on-Stone Provincial Park, Alberta, from the Deadhorse Coulee Member of the Milk River Formation (late Santonian). Detailed locality information is on record with the Royal Ontario Museum.
Gryphognathus morrisoni from the Santonian Milk River Formation is approximately 8 Ma older than U. koppelhusae and appears to be closely related to it. Gryphognathus appears to share with Unescoceratops the presence of a predentary symphysial “chin”, but, owing to breakage, we have chosen to code this character as indeterminate.
Additionally, the shape of the teeth and the degree of curvature of the ventral margin cannot be determined. We acknowledge that the holotype specimen, ROM 56635, is incomplete; however, we advocate recognition of the new taxon based on the presence of two autapomorphies; Gryphognathus appears to differ from Unescoceratops and all other leptoceratopsids in having a relatively deeper jaw, and in the shape of the posterior border of its predentary symphysial contact where it merges with the ventral margin.
As reconstructed, the foreshortened dentary of ROM 56635 is deeper than that of U. koppelhusae, and appears to be as deep, or deeper, than any other leptoceratopsid
Lower right jaw fragments of Gryphoceratops were discovered in southern Alberta in 1950 by Levi Sternberg while he worked for the Royal Ontario Museum. Gryphoceratops morrisoni represents the oldest known leptoceratopsid (∼83 Ma), and probably represents the smallest adult-sized ceratopsian known from North America it had a shorter and deeper jaw shape than any other leptoceratopsid. Based on unique characteristics of the jaw and its size, Ryan et al believe that Gryphoceratops was an adult that did not exceed one-half meter in length. This means it is the smallest adult-sized horned dinosaur in North America and one of the smallest adult-sized plant-eating dinosaurs known.
Etymology
The genus is named for Gryphon, a mythological Greek figure with the body of a lion and the head of an eagle, which is a reference to the animal s beaked face. The species name honors Ian Morrison, a Royal Ontario Museum technician, who discovered how the bones fit together.
Diagnosis
Gryphognathus is a small leptoceratopsid that can be differentiated from all other members of the clade in having the deepest dentary at midpoint relative to tooth row length, and a sigmoidally curved posterior margin of the predentary symphysial contact that terminates as a butt suture with a posterior margin that is almost perpendicular to the ventral dentary margin at the midpoint of the tooth row. Gryphognathus shares with Leptoceratops, Prenoceratops and Unescoceratops the presence of the predentary flange. Gryphognathus shares with Unescoceratops and Cerasinops the recumbent coronoid process, and shares with Unescoceratops the shape of the ventral dentary margin.
The genus is named for Gryphon, a mythological Greek figure with the body of a lion and the head of an eagle, which is a reference to the animal s beaked face. The species name honors Ian Morrison, a Royal Ontario Museum technician, who discovered how the bones fit together.
Diagnosis
Gryphognathus is a small leptoceratopsid that can be differentiated from all other members of the clade in having the deepest dentary at midpoint relative to tooth row length, and a sigmoidally curved posterior margin of the predentary symphysial contact that terminates as a butt suture with a posterior margin that is almost perpendicular to the ventral dentary margin at the midpoint of the tooth row. Gryphognathus shares with Leptoceratops, Prenoceratops and Unescoceratops the presence of the predentary flange. Gryphognathus shares with Unescoceratops and Cerasinops the recumbent coronoid process, and shares with Unescoceratops the shape of the ventral dentary margin.